Dry processing of photographic emulsions



Oct. 19, 1965 J. s. YUDELSON ETAL 3,212,896

DRY PROCESSING OF PHOTOGRAPHIC EMULSIONS Filed June '7, 1961 HEATSENSITIVE CAPSULES a 12 x FIG I Q Q A PHOTOGRAPHIC EMULSION GELATIN HEATSENSITIVE cAPsuLEs FIG 2 PHOTOGRAPH/C EMULSION SUPPORT GELATIN [2 HEATSENSITIVE CAPSULES I I PHOTOGRAPH/C EMULSION GELATIN I3 HEAT SENSITIVECAPSULES I2 SUPPORT IO HEATED ROLLER I7 I6 HEATED ROLLER FIG 5 I8 HEATEDRoLLER 2O HEAT SENSITIVE ELEMENT 2 X A JOSEPH s- YUDELSON RALPH w-BAXENDALE I9 HEATED ROLLER INVENTORS BY %MM AT TORNE YS United StatesPatent 3,212,896 DRY PROCESSING OF PHOTOGRAPHIC EMULSIONS Joseph S.Yudelson and Ralph W, Eaxendale, Rochester,

N.Y., assignors to Eastman Kodak Company, Rochester, N.Y., a corporationof New Jersey Filed June 7, 1961, Ser. No. 115,579 14 Claims. (Cl.96-63) This invention relates to photography and particularly to the dryprocessing of photographic emulsions. Still more particularlythe presentinvention relates to incorporated thermally sensitive capsulescontaining photographic processing agents.

In photography, it is the usual procedure to employ liquid processingsolutions in the processing of exposed photographic emulsions to formsilver images. Liquid processing requires special equipment and usuallyrather elaborate facilities. According to the present invention, a Wayhas been found in which an exposed photographic emulsion layer canbeprocessed without requiring liquid processing compositions, in fact, thepresent process is substantially a dry process requiring only theapplication of mild heat.

It is, therefore, an object of the present invention to providephotographic materials that can be dry processed. Another object is toprovide photographic materials having incorporated heat-sensitivecapsules containing liquid photographic processing agents. A furtherobject is to provide a dry method of processing such materials. Stillanother object is to provide a method for preparing the heat-sensitivecapsules of the invention and incorporating same in a photographicemulsion layer.

These objects are accomplished by incorporating in silver halidephotographic emulsion layers heat-sensitive coacervate-formed capsulescontaining (1) a photographic processing agent, and (2) a heatdecomposable organic nitrogenous compound containing at least onenitrogento-nitrogen linkage, said compound being capable of generatinggas upon thermal exposure sufficient to burst said capsule and releaseitsinternal contents.

Typical nitrogen-to-nitrogen linkages which unexpectedly were found tobe sufficiently gas-producing accord- .ing to the invention whenthermally exposed to temperatures acceptable for use in a photographicapplication, comprise, for example, a

linkage. Organic compounds having nitrogen-to-nitrogen linkages of thistype produce copious amounts of nitrogen gas when thermally exposed to atemperature in the range from about 60 C. to about 150 C.

The temperature that can be safely employed in the bursting of capsulesincorporated in particular emulsions depends largely upon the emulsioninvolved. It is Well known that some emulsions, depending most usuallyupon the process used in preparing them and the make-up of the emulsion,are more sensitive to heat than are other emulsions. For example, wherethe more highly sensitive emulsions are used, a blowing agent of higherthermal sensitivity, i.e., generates gas at a lower temperature, shouldbe used. Similarly, emulsions of lower sensitivity can tolerate highthermal exposures and blowing agents having lower thermal sensitivitiescan be used.

To be suitable for use in the present invention, the heat-decomposablesubstances of this invention should be solid at room temperature andshould be inert regarding the capsular wall material and the contents ofthe capsule. The heat-decomposable substances should not react with theinternal contents of the capsule nor should the gas evolved onheat-decomposition react with either the internal contents of thecapsule or the surrounding medium. The substances likewise should notinterfere chemically with the normal reaction of photographicsensitizers, desensitizers, chemical processing solutions, etc. Moreoverthe substances should not accelerate nor in any way substantially affectthe normal processing of photographic reactions. Still further the heatdecomposable substances should be non-toxic and odorless, as shouldtheir decomposition products. The substances and their decompositionproducts should also be substantially colorless, since their use in themanufacture of many types of photographic materials include those whichmust be light in color and free of stain. The heat decomposablesubstances of this invention will be referred to herein as blowingagents. For use in the invention these agents should be miscible inwater-immiscible solvents. Solvents of this type include the naturaloccurring oils such as olive oil, i.e., coconut oil, castor oil, fishoils; animal oils such as sperm oil; vegetable oil; mineral oils, suchas petroleum lubricating oil; synthetic compounds such as chlorinateddiphenyl, methylsalicylate, di-n-butylphthalate, etc. Other suitablesolvents are disclosed in US. Patent 2,800,457, patented July 23, 1957.

Suitable heat-decomposable organic substances having anitrogen-to-nitrogen linkage according to the present invention comprisethe following classes of compounds.

A. Azobis (alkanenitriles) as represented by the following generalformula:

wherein R R R and R, can each represent a hydrogen atom, a lower alkylgroup containing from 1 to 4 carbon atoms, such as methyl, ethyl,propyl, isopropyl, etc., an aryl group such as phenyl, naphthyl, and asubstituted aryl group having substituents such as amino (NH a halogenatom, such as chlorine, bromine, etc., a lower alkyl group having from 1to 4 carbon atoms such as methyl, ethyl, propyl, isopropyl, etc., and alower alkoxy group, such as methoxy, ethoxy, etc.

B. N-nitroso-N-alkylalkaneamides and N-nitroso-N-alkylalkanesulfonamides having the general formula:

NO n

wherein G is -CO or 40 R is a lower alkyl group having from 1 to 4carbon atoms, andn is the integer, 1 or 2. When n is 1, R, can representan alkyl group having from 3 to 10 carbon atoms; an aryl group such asphenyl, naphthyl; a substituted aryl group having substituents such as ahalogen atom (e.g. chlorine, bromine), and a lower alkoxy group such asmethoxy, ethoxy, etc. When n is 2, R represents an alkylene group havingfrom 3 to 10 carbon atoms; an arylene group such as phenylene,naphthylene; a substituted arylene group having substituents such as ahalogen atom ,(e.g., chlorine, bromine), a lower alkyl group having from1 to 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, etc., anda lower alkoxy group, such as methoxy, ethoxy, etc.

3 C. Aroyl azides having the general formula:

9 Y- C-Na wherein R represents a hydrogen atom; a hydroxyl group; ahalogen atom (e.g., chlorine, bromine, etc.); an amino group; a loweralkyl group having from 1 to 4 carbon atoms, such as methyl, ethyl,propyl, isopropyl, etc.; a lower alkoxy group having from 1 to 4 carbonatoms, such as methoxy, ethoxy, etc.; Y and Z can each represent ahydrogen atom; a hydroxyl group; an alkyl group containing from 1 to 4carbon atoms, Y and Z together can represent the atoms necessary tocompelte a benzene ring, and Y and Z together can represent the atoms ofa benzene ring which can have substituents thereon such as an aminogroup; a lower alkyl group having from 1 to 4 carbon atoms; a hydroxylgroup, etc.

D. Disulfonhydrazide such as bi(aryl)-p,p'-disulfonhydrazide having thegeneral formula:

wherein R and R can each represent a hydroxyl group; a halogen atom(e.g., chlorine, bromine, etc.); a lower alkyl group having from 1 to 4carbon atoms, such as methyl, ethyl, propyl, isopropyl, etc.; a loweralkoxy group having from 1 to 4 carbon atoms, such as methoxy, ethoxy,etc.; and Q can represent a sulfur atom, an oxygen atom, a (CH groupwherein n is an integer from 1 to 10, and a Ills C group wherein each Rand R comprise an alkyl radical having from 1 to 10 carbon atoms.

Other heat-decomposable substances which are gasproducing when thermallyexposed comprise certain diazonium salts such as those described in US.Patents 2,908,572, October 13, 1959; 2,822,271, February 4, 1958; and2,805,159, September 3, 1957.

Certain organic peroxides are also gas-producing when thermally exposed.These include benzoyl peroxide, acetylbenzoyl peroxide and di(te1tiaryalkyl) peroxide. These peroxides and others are disclosed in US. Patents2,403,758, July 9, 1946; 2,381,561, August 7, 1954; 2,160,903, June 6,1939; and 2,109,595, March, '1 1938.

Photographic processing solutions and other materials used in aphotographic application according to the present invention and whichare encapsulated along with blowing agents of this invention shouldlikewise be miscible in water-immiscible solvents. Typical photographicdevelopers of this type include, for example, 4-pheny1 catechol, 4,4dimethyl 3 phenyl-3-pyrazo1idone; octadecyloxybenzaldehyde Schiif baseof N-ethyl-N-hydroxyethyl-p-phenylenediamine; and the like. Otherphotographic processing agents which can be encapsulated along with ablowing agent of this invention include 5- carboxymethyl mercaptobenzalacetophenone, benzotriazole, etc.

By employing a rapid encapsulation process, water soluble processingagents can also be utilized, such as hydroquinone, particularly whensuspended in a viscous water-immiscible solvent.

In preparing the capsules of this invention, a hydrophilic colloid isused which possesses the ability to disperse a Water-immiscible solvent.The capsules incorporating the blowing agents and photographic compoundsof the invention are formed essentially by a process com- 4 prisingcoacervation. Suitable processes of this type have been described in US.Patent 2,800,457, issued July 23, 1957. One of such processes which hasparticular relevance to the present invention will be described in thefollowing paragraph.

In this invention, a suitable blowing agent and an oilsoluble oroil-dispersable photographically employed compound are mixed thoroughlyin a water-immiscible solvent. In the case where either or both theaddenda are dispersed in the water-immiscible solvent, i.e., oil, suchaddenda should be colloidal in size. The waterimmiscible solventcontaining the addenda is then dispersed in a hydrophilic colloid suchas gum arabic. The dispersion is then mixed with an aqueous sol ofanother colloid such as pigskin gelatin. Encapsulation of thewater-immiscible solvent containing the blowing agent andphotographically employable material then results when the dispersion isdiluted with water at a certain pH. Thereafter the capsules can begelled by treatment with cold water or by keeping in a cold environment.The suspension of capsules can be concentrated or diluted withwater-soluble binders, etc., so that mixtures prepared thereby can beused according to processes of the present invention. Typical substancesthat can be incorporated in the capsules according to the presentinvention comprise, for example, photographic processing reagents, suchas developers, fixers, combined developers and fixers, etc.;color-forming compounds such as color-couplers, etc.; color-producingsubstances such as dyes; color-producing components of dyes;photographic sensitizers, photographic desensitizers, etc.

The heat-sensitive capsules of the present invention can also beemployed in a processing web whereby the web is placed in thermalcontact with a photographic emulsion layer to be processed. Webs of thetype contemplated can be prepared by coating on a support heatsensitivecapsules suspended in a suitable binder such as gelatin, syntheticresins, and the like. In a process of this type, the web is normallyplaced in contact with the exposed emulsion layer and the two-plyassembly passed between heated rollers to give the required thermalexposure. After allowing sufiicient time for the particular processingstep involved to take place, the emulsion layer is removed from the weband the next processing step carried out.

One manner in which the heat-sensitive capsules of our invention can beemployed in a photographic application will be further illustrated byreference to the accompanying drawings. In FIG. 1 thereof is shown asectional view of a support 10 coated with a silver halide photographicemulsion layer 11 containing heat-sensitive capsules 12 uniformlydispersed throughout the emulsion layer. In FIG. 2 is shown a sectionalview of a silver halide emulsion layer 11 coated on a support 10 whereinthe emulsion layer 11 is overcoated with a gelatin layer 13 which hasuniformly distributed therethrough heatsensitive capsules 12. FIG. 3 ofthe accompanying drawing shows a support 10 coated with a gelatin layer13 and having uniformly distributed therethrough heat-sensitive capsules12. The heat-sensitive element of FIG. 3 is a non-light-sensitiveelement or web and can be used in the processing of photographicmaterials.

FIG. 4 of the accompanying drawing shows a manner of treating a silverhalide photographic emulsion layer with a non-light-sensitive element asshown in FIG. 3. In FIG. 4 a silver halide emulsion layer 11 coated on asupport 10 is pressed into heat contact with a heat-sensitive layer 13coated on a support 10 and having the heatsensitive capsules 12uniformly, dispersed therethrough. At the interface between thephotographic element and the treating element of FIG. 4 an aqueoussolution 15 is provided so that sufficient water is assured in carryingout the process. The emulsion element and the treating element as shownin FIG. 4 are passed in pressure contact between heated rollers 16 and17.

In FIG. 5 is shown a pair of heated rollers 18 and 19 which provide heatfor the rupturing of the capsules contained in element 20. The elementof FIG. 5 can be a heat-sensitive element as shown in FIGS. 1 and 2 ofthe accompanying drawing or the apparatus of FIG. 5 can be utilized toprovide the heat required where a conventional silver halide emulsionlayer is processed with a heatsensitive element as shown in FIG. 3. Itis apparent also that, by providing a pair of rollers in tandem,different processing temperatures can be provided. For example, byincorporating into the heat-sensitive layer capsules of both fixer anddeveloper and by contacting such a heat-sensitive element with aphotographic layer to be processed, the first pair of rollers couldprovide the temperature required to burst the capsules containing adeveloper and the second pair of rollers, which would be in tandemarrangement with the first, could be provided with a temperaturesufiicient to burst the capsules containing a photographic fixer. Itwill be apparent that a wide variety of applications can be made of thepresent invention.

The invention will now be described by reference to the followingexamples.

Example 1 'To 45 ml. of polyglycol (ll-200 Dow Chemical Company) formedby the condensation of glycerol and propylene oxide and having amolecular weight of about 2700, was added 5 grams of 4-phenylcatecholand 2 grams of p,p'-oxy-bis(benzene sulfonyl hydrazide). The solutionwas then dispersed in 80 grams of 11.1 percent gum arabic and emulsifiedfor 10 minutes, at the end of which time the droplet size varied fromabout 0.7 to about 5 microns. The dispersion was then added to 80 gramsof an 11.1 percent solution of pigskin gelatin, the pH of which wasadjusted so that the final pH of the mixture was 4.7 to 5.0. Thetemperature was kept at 50 to 55 degrees C. While rapidly stirring themixture, 178 ml. of water was added. The mixture, while beingcontinuously agitated, was then added to a rapidly agitated cold waterbath which contained about 2.5 liters and was held at a temperature of 3to 5 degrees C. The highly swollen coacervate gelled around each oildroplet. A minute amount of an anti-foaming agent (SS-60-GeneralElectric Company) was added to the chilled bath before the addition ofthe coacervate to eliminate foaming. The mixture was then stirred forapproximately minutes to assure separation of each capsule. The capsuleswere then hardened by the adding of 40 grams of a 25 percent aqueousglutaraldehyde solution and stirring for three hours. A 10 percentsodium acetate solution was then added to the suspension while stirringuntil coagulation occurred. The coagulum was then washed for three hourswith cold water. The wet coagulum was then drained of excess water andstored, until ready for addition to a silver halide emulsion prepared asfollows:

Solutions were made of (A) 25 grams of gelatin in 1 liter of water at 40C. (B) 100 grams silver nitrate in 500 ml. water at 20 C. and (C) gramsof sodium chloride in 365 ml. of water. Solutions B and C were runsimultaneously into solution A at a uniform rate while stirring thelatter over a period of about 10 minutes; solution B was not allowed torun in faster than C. The solution was then stirred continuously withmild agitation while holding at C.

For addition to the silver halide emulsion dispersion, grams of thecoagulum of paragraph 1 of this example was mixed with 75 ml. of hotwater, 10 ml. of a 7 percent gelatin solution, and two drops of anantifoaming agent (SS--General Electric Company). The mixture was thendispersed with a Waring Blendor for 20 seconds and added to the emulsionsolution while stirring. By adding the coagulum preparation slowly tothe emulsion solution while stirring, the capsules became disperseduniformly throughout the emulsion.

The emulsion was then coated on cellulose acetate film base over an areaof about 500 square feet and dried. The film was exposed to a subject bycontact with a negative having opaque areas and clear areas. Thereafterthe exposed element containing the encapsulated developing agent in theemulsion layer was passed between a pair of heated rollers to give aninternal temperature of at least C. The exposed and developed emulsionlayer was fixed in a conventional manner to produce a positive image ofgood quality.

Example 2 To 45 ml. of a 5 percent solution ofa.zo-bis(isobutyronitrile) in di-n-butylphthalate was added 5 grams of4,4- dimethyl-3-phenyl-3-pyrazolidone which was then dispersed into 80grams of 11.1 percent gum arabic and emulsified until the droplet sizevaried from about 0.8 to about 6 microns. The dispersion was then addedto 80 grams of 11.1 percent solution of gelatin at a temperature of 45to 50 C. The pH was adjusted to 4.8. While rapidly stirring, 178 ml. ofwater was added to the mixture. The mixture was then added to 3 litersof cold (5 C.) water in order to gel the coacervate. The capsules werehardened by the addition of 40 grams of a 25 percent aqueousglutaraldehyde solution to the suspension and stirred for three hours.The suspension was then coagulated by means of sodium acetate afterwhich the coagulum was washed for three hours with cold water. Afterdraining to remove excess water, 50 grams of the coagulum was mixed with75 ml. of hot water, 10 ml. of a 7 percent gelatin solution and 2 dropsof GE SS-60 Anti-Foaming Agent. The mixture was dispersed with a WaringBlendor for 20 seconds, then mixed with 0.3 ml. of a 2 percent solutionof Duponol dispersing agent, and coated on a gelatin subbed celluloseacetate film base to give a coverage of 3.1 grams per square foot. Thecoating consisted of closely-packed capsules which adhered to each otherby virtue of partial fusion of their walls. A small amount of gelatinwas added to disperse the capsules and also bind the capsules togetherin the dried film.

Strips of Kodabromide Paper were then given a suitable exposure, andpressed in heat contact (at a temperature of about C.) with thedeveloper-capsule web prepared according to the description in the aboveparagraph. After about a two-minute interval the capsular web wasremoved from the emulsion layer of the exposed photographic paper. Thepaper was then fixed in a conventional manner to reveal a high-qualitywarm-tone photographic negative image.

Example 3 A 4 percent Aroclor #1232 solution of Z-carbazido-lnap htholwas made. (The colorless chlorinated hydrocarbon solvent, Aroclor #1232,was purchased from Monsanto Company.) To the solution was added SudanIII colorant at a 1.0 percent concentration. The mixture was thenencapsulated, hardened, separated, and drained of excess water accordingto the method described in Example 1.

The capsules were then dispersed in a 7 percent gelatin solution towhich was added 15 percent (based on weight of the gelatin) :of aplasticizer, bis(2-(2-methoxyethoxy) ethyl) ether. The ratio of thecapsules to gelatin was 2:1 by Weight. The mixture was then coated on astrip of Kodak Verifax copy paper and given a therrnographic exposure insurface contact with a printed original. A short exposure reproduced acopy of the original on the copy paper.

Similar results were obtained using Z-carbazido-llacetoxy-naphthalene.

Example 4 To a 10 percent solution ofN,N'dinitroso-N,'N-dimethylgluta-ramide in Aroclor #1232 solvent, 20.0grams per liter of ,B-canboxymethyl mercapto b'enzal'aeetophenone fixingagent was added. The solution was then encapsulated, hardened, separatedand drained of excess water as in Example 1.

75 grams of the capsules prepared according to the above paragraph andcontaining the blowing agent and water-insoluble fixing agent wasdispersed in a silver halide emulsion prepared as in Example 1. Themixture was then dispersed with a Waring Blendor for 20 seconds and thenadded to the emulsion solution as in Example '1.

After coating the emulsion on cellulose acetate filrn base in aconventional manner and exposing to a negative image, the exposedelement containing the encapsulated blowing agent and fixing agent wasdeveloped in a photographic developer of the following composition:

N-methylap-aminophenolsulfate "grams" 2.2 Hydroquinone do 8.8 Sodiumsulfite (anhydrous) do 72.0 Sodium carbonate (monohydr-ate) do 130.0Potassium bromide do 4.0 Water to make liter 1.0

After developing, the element was washed and passed between a pair ofheated rollers. After washing, a developed and fixed negative image ofgood quality resulted.

The N,N' dinitnoso-N,N'dimethylglutararnide was prepared by thenitrosation of NlN'-dime0hylglutar-amide, which in turn was made byreacting methylamine with N,N-dimethylglutarate.

Similar results were obtained using N,N'-:dinitroso-N,N'-dimethylsuccinamide prepared by the nitrosatio-n ofN,-N-dimethylsuccinamide.

In the present invention, the blowing agents employed evolve copiousamounts of gas when exposed to a temperature in the range from about 60C. to about 15 C. Ordinarily an exposure temperature in the range fromabout 70 C. to about 130 C. results in copious gas being evolved by theblowing agents. Accordingly, in this comparatively narrow temperaturerange, the optimum ternperature for processing can be reached easily andquickly by a number of ways. For example, passing the processing elementbetween a pair or heated rollers, heating on a hot plate, etc., can:give good results. In certain cases it may be advantageous to expose aphotographic element or a document reproducing element incorporating theheat-sensitive capsules of this invention to infrared radiation such asthat provided by a thermographic exposure. Naturally, the more suitablemeans for any particular application of this invention would need to beselected for the particular processing or development step contemplated.In any event, as shown above, the incorporation of at least one of theblowing agents of this invention gave substantially immediate andcomplete rupturing of the capsule so that it was necessary to maintainthe elevated temperature :for only a very brief period.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be efiected within the scope and spirit of theinvention as described hereinabove and as defined in the appendedclaims.

We claim:

'1. A photographic element comp-rising a silver halide emulsion andintegral there-With a water-permeable, hydrophilic colloid layer on asupport, said layer comprising ('1) a continuous phase or"water-permeable, hydrophilic colloid, and uniformly dispersed throughoutsaid continuous phase,

(2) a discontinuous phase of heat sensitive capsules each comprising acore containing (a) a solution in an oily, water-immiscible solventtfirom the group consisting of silver halide photoopers and fixers,

(b) a heat decomposable, gas-producing, organic compound compatible withsilver halide photographic emulsions, having at least 2 nitrogen atomslinked together, said nitrogen atoms being liberated by heat at atemperature of about 60 C. to about C. to produce nitrogen gas, and

(c) surrounding said core, a shell of a gelatin-gum arabic coacervate.

2. A photographic silver halide emulsion layer on a support, said layercomprising (1) a continuous phase of organic water-permeable hydrophiliccolloid containing light-sensitive silver halide salts and uniformlydispersed throughout said continuous phase,

(2) a discontinuous phase of heat sensitive capsules each comprising acore containing '(a) a solution in an oily, water-immiscible solvent ofa silver halide processing reagent selected hrorn the group consistingof silver halide photographic developers, fixers, and combineddevelopers and fixers,

(b) a heat-decomposable, gas-producing, organic compound compatible withsilver halide emulsions, having at least 2 nitrogen atoms linkedtogether, said nitrogen atoms being liberated by heat at a temperatureof about 60 C. to about 150 C. to produce nitrogen gas, and

(c) surrounding said core, a shell of a gelatin-gum arabic coacervate.

3. A water-permeable, hydrophilic colloid layer on a support, said layercomprising (1) a continuous phase of water-permeable, hydrophiliccolloid, and uniformly dispersed throughout said continuous phase, (2) adiscontinuous phase or heat sensitive capsules each comprising a corecontaining (a) a solution in an oily, water-immiscible solvent of atleast one silver halide processing reagent selected from the groupconsisting of silver halide photographic developers, fixers, andcombined developers and fixers,

(b) a heat-decomposable, gas-producing, organic compound compatible withsilver halide photographic emulsions, having at least 2 nitrogen atomslinked together, said nitrogen atoms being liberated by heat at atemperature of about 60 C. to about 150 C. to produce nitrogen gas, and

(c) surrounding said core, a shell of a gelatin-gum arabic coacervate.

4. A water-permeable, hydrophilic colloid layer on a support, said layercomprising (1) a continuous phase of water-permeable, hydrophiliccolloid and uniformly dispersed throughout said continuous phase, (2) adiscontinuous phase of heat sensitive capsules each comprising a corecontaining (a) a solution in an oily, water-immiscible solvent of atleast one silver halide photographic processing reagent selected fromthe group consisting of silver halide photographic developers, fixers,and combined developers and fixers,

(b) a heat decornposabrle, gas-producing, organic compound compatiblewith silver halide photographic emulsions, having at least 2 nitrogenatoms linked together, said nitrogen atoms being liberated by heat at atemperature of about 60 C. to about 150 C. to produce nitrogen gas, saidcompounds being selected from the ing of sulfur, oxygen and alkylenehaving from 1 to 10 carbon atoms, and

(c) surrounding said core, a shell of a gelatin-gum iarabic coacervate.

10 consisting of azobis(alkanenitriles) as represented by the followingformula:

R1 R3 R1 Ra EC N= NEO(:JN=NJJCEN R2 R4 R: 1:! wherein R R R and R eachrepresents hywherein R R R and R each represents hydrogen, lower alkylcontaining from 1 to 4 cardrogen, lower alkyl containing from 1 to 4carbon atoms, phenyl and a substituted aryl group bon atoms, phenyl anda substituted aryl group having substituents selected from the groupconhaving substituents selected from the group sisting of halogen, loweralkyl having from 1 to consisting of halogen, lower alkyl having from 4carbon atoms and lower alkoxy having from 1 to 4 carbon atoms and loweralkoxy having 1 to 4 carbon atoms; carbazido-aryl compounds from 1 to 4carbon atoms; carlbazido-aryl comhaving the following formula: poundshaving the following formula:

i O Y- C---Na Y Hi-N3 Y 2 wherein R represents a member from the groupwherein R represents a member from the group consisting of hydrogen,hydroxyl, halogen, lower consisting of hydrogen, hydroxyl, halogen,alkyl having from 1 to 4 carbon atoms, l w r lower alkyl having from 1to 4 carbon atoms, ialkoxy having from 1 to 4 carbon atoms, Y and loweralkoxy having from 1 to 4 carbon atoms, Z each represents hydrogen,hydroxyl and alkyl Y and Z each represents hydrogen, hydroXyl containingfrom 1 to 4 can-bon atoms, Y and Z and alkyl containing from 1 to 4carbon atoms, together represent the atoms of a benzene ring Y and Ztogether represent the atoms of a benhaving .substit-uents thereonselected from the zene ring having substituents thereon selected :g-roup consisting of lower alkyl having from 1 from the group consisting oflower alkyl having to 4 carbon atoms, lower alkoxy having from 1 from 1to 4 carbon atoms, lower alkoxy having to 4 carbon atoms, halogen andhydroxyl; N- from 1 to 4 carbon atoms, halogen and hynitroso compoundshaving the following fordroxyl; N-nitroso compounds having the folrnula:lowing formula:

(FRFC O*N R3 R -NC O-R2-C ONRa N0 N0 n r'ro wherein R and R eachrepresents alkyl having from 1 to 4 canbon atoms and R representswherein R and R each represents alkyl havalkylene having dirom 3 to 10carbon atoms; and ing from 1 to 4 carbon atoms and R representsbis-phenolsulfonyl hydrazide having the follow- 40 alkylene having from3 to 10 carbon atoms; i f l and bis-phenolsulfonyl hydrazide having theO 0 following formula: H II II E H N-N s- Q- s-N-NH, 0 0

i HNfiis' Q NH B1 In 2 M Q Q" 2 wherein R and R each representshydhoxyl, 0 O halogen, lower alkyl having from 1 to 4 carbon atoms,lower alkoxy having from 1 to 4 carbon wherein 1 and 2 each representshydroxyl, atoms and Q is selected from the group consistg lower alkylhaving from 1 to 4 Carbon atoms, lower alkoxy having from 1 to 4 carbonatoms and Q is selected from the group consisting of sulfur, oxygen andalkylene having from 1 to 10 carbon atoms, and

(c) surrounding said core, a shell of a gelatin-gum arabic coacervate.6. A photographic silver halide emulsion layer on a support, said layercomprising (1) a continuous phase of water-permeable, hydrophiliccolloid and uniformly dispersed throughout said continuous phase, (2) adiscontinuous phase of heat sensitive capsules each comprising a corecontaining 5. A photographic element comprising a silver halide emulsionon a support and integral therewith a waterpermeable hydrophilic colloidlayer, said layer comprislng (l) a continuous phase of water-permeable,hydrophilic colloid, and uniformly dispersed throughout 0 saidcontinuous phase,

(2) a discontinuous phase of heat sensitive capsules each comprising acore containing (a) a solution in an oily, water-immiscible solvent (a)a solution of an oily, water-immiscible solvent of at least One silverhalide photographic procof t least one silver halide photographicprocessing reagent selected from the group consistessing reagentselected from the group consisting of silver halide photographicdevelopers, ing of silver halide photographic developers, fixers, andcombined developers and fixers, fiXeFS and Combined developers andfiXeIS, (b) a heat-decomposable, gas-producing, organic aheat-decomposable, gas-Producing, Organic compound compatible withsilver halide photocompound compatible with silver halide photographicemulsions, having at least 2 nitrogen graphic emulsions, having at least2 nitrogen atoms linked together, said nitrogen atoms being atoms linkedtogether, said nitrogen atoms being liberated by heat at a temperatureof about 60 liberated by heat at a temperature of about 60 C. to about150 C. to produce nitrogen gas, C. to about 150 C. to produce nitrogengas, said compounds being selected from the class said compounds beingselected from the class wherein R R R and R each represents hydrogen,lower alkyl containing from 1 to 4 carbon atoms, phenyl and asubstituted aryl group having substituents selected from the groupconsisting of halogen, lower alkyl having from 1 to 4 carbon atoms andlower alkoxy having from 1 to 4 carbon atoms; carbazido-aryl compoundshaving the following formula wherein R represents a member from thegroup consisting of hydrogen, hydroxyl, halogen, lower alkyl having from1 to 4 carbon atoms, lower alkoxy having from 1 to 4 carbon atoms, Y andZ each represents hydrogen, hydroxyl and alkyl containing from 1 to 4carbon atoms, Y and Z together represent the atoms of a benzene ringhaving substituents thereon selected from the group consisting of loweralkyl having from 1 to 4 carbon atoms, lower alkoxy having from 1 to 4carbon atoms, halogen and hydroxyl; N-nitroso compounds having thefollowing formula:

wherein R and R each represents alkyl having from 1 to 4 carbon atoms,and R represents alkylene having from 3 to carbon atoms; andbis-phenolsulfonyl hydrazide having the following formula:

wherein R R R and R each represents hydrogen, lower alkyl containingfrom 1 to 4 carbon atoms, phenyl and substituted aryl havingsubstituents selected from the group consisting of halogen, lower alkylhaving from 1 to 4 carbon atoms and lower alkoxy having from 1 to 4carbon atoms.

, .12 a 8. A hydro-philic colloid layer of claim 1 wherein saidgas-producing compound is a carbazido-aryl compound having the formula:

Br I

O Y LN,

wherein R represents .a member from the group consisting of hydrogen,hydroxyl, halogen, lower alkyl having from 1 to 4 carbon atoms, loweralkoxy having from 1 to 4 carbon atoms, Y and Z each representshydrogen, hydroxyl and alkyl containing from 1 to 4 carbon atoms, Y andZ together represent the atoms necessary to complete a benzene ringhaving substituents thereon selected from the group consisting of loweralkyl having from 1 to 4 carbon atoms, lower alkoxy having from 1 to 4carbon atoms, halogen and hydroxyl.

9. A hydrophilic colloid layer of claim 1 wherein said gas-producingcompound is a N,N'-dinitroso-N,N- dialkylalkylamide having the formula:

wherein R and R each represents alkyl having from 1 to 4 carbon atomsand R represents alkylene having from 3 to 10 carbon atoms.

10. A hydrophilic colloid layer of claim 1 wherein said compound is abis-phenolsulfonyl hydrazide having the formula:

wherein R and R each represents hydroxyl, halogen, lower alkyl havingfrom 1 to 4 carbon atoms, lower alkoxy having from 1 to 4 carbon atoms,and Q is selected from the group consisting of sulfur, oxygen andalkylene having from 1 to 10 carbon atoms.

11. Heat sensitive capsules formed by the steps comprising e (1) makinga solution of water-immiscible solvent containing at least one silverhalide photographic reagent selected from the group consisting of silverhalide photographic developers, fixers and combined developers andfixers and a heat-decomposable, gasproducing, organic compoundcompatible with silver halide photographic emulsions, having at least 2nitrogen atoms linked together, which decomposes at a temperature atabout 60 C. to about C. to release nitrogen gas,

(2) making an aqueous sol of gum arabic,

(3) emulsifying in said sol, the said water-immiscible solvent,

(4) adding and stirring into the emulsion an aqueous sol of pigskingelatin, and

(5) adding sufficient water to bring the emulsion into the coacervateregion defined by the occurrence of the formation of said capsules.

12. A process of obtaining a silver image from an exposed silver halideemulsion comprising contacting the exposed silver halide emulsionagainst a water-permeable, hydrophilic colloid layer on a support, saidlayer comprising (1) a continuous phase of water-permeable, hydrophiliccolloid and uniformly dispersed throughout said continuous phase,

(2) a discontinuous phase of heat sensitive capsules each comprising acore containing (a) a solution in an oily, water-immiscible solvent ofat least one silver halide photographic developer,

(b) a heat-decomposable, gas-producing, organic compound compatible withsilver halide emulsions, having at least 2 nitrogen atoms linkedtogether, said nitrogen atoms being liberated by heat at a temperatureof about 60 C. to about 150 C. to produce nitrogen gas, and

(c) surrounding said core, a shell of a gelatingum arabic coacervate,

thermally treating the exposed silver halide emulsion in contact withthe said hydrophilic colloid layer to a temperature in the range fromabout 60 C. to about 150 C. for a sufiicient time to burst the said heatsensitive capsules and stabilizing the silver halide emulsion.

13. A process of obtaining the silver image from an exposed silverhalide emulsion on a support and having integral with the emulsion aWater-permeable, hydrophilic colloid layer, said layer comprising (1) acontinuous phase of water-permeable, hydrophilic colloid and uniformlydispersed throughout said continuous phase,

(2) a discontinuous phase of heat sensitive capsules each comprising acore containing (a) a solution in an oily, Water-immiscible solvent ofat least one silver halide photographic developer,

(b) a heat-decomposable, gas-producing, organic compound compatible withsilver halide photographic emulsions, having at least 2 nitrogen atomslinked together, said nitrogen atoms being liberated by heat at atemperature of about 60 C. to about 150 C. to produce nitrogen gas, and

(c) surrounding said core, a shell of a gelatingum arabic coacervate,

by heating the exposed silver halide emulsion to a temperature in therange from about 60 C. to about 150 C. for a suflicient time to burstthe said heat sensitive capsules and the silver halide emulsion.

14. A process of obtaining a silver image from an exposed silver halideemulsion layer comprising (1) a continuous phase of organicwater-permeable hydrophilic colloid containing light sensitive silverhalide salts and uniformly dispersed throughout said continuous phase,

14 (2) a discontinuous phase of heat sensitive capsules each comprisinga core containing (a) a solution of an oily, water-immiscible solvent ofat least one silver halide photographic developer, (b) aheat-decomposable, gas-producing, organic compound compatible withsilver halide photographic emulsions, having at least 2 nitrogen atomslinked together, said nitrogen atoms being liberated by heat at atemperature about C. to about C. to produce nitrogen gas, and (c)surrounding said core, a shell of gelatingum arabic coacervate, byheating the exposed silver halide emulsion to a temperature in the rangefrom about 60 C. to about 150 C. for a suflicient time to burst the saidheat sensitive capsules and stabilizing the silver halide emulsion.

References Cited by the Examiner UNITED STATES PATENTS 2,699,392 1/55Herrick 96-91 2,703,756 3/55 Herrick 96-91 X 2,774,668 12/56 Rogers96-29 2,797,201 6/57 Veatch. 2,965,484 12/60 Tulagin 96-98 X 3,001,8739/61 Floris 96-28 X 3,041,287 6/62 Katchen 167-83 X 3,041,288 6/62Anthony 167-83 3,116,148 12/63 Miller 96-27 FOREIGN PATENTS 580,909 8/59Canada.

OTHER REFERENCES NCR Capsules Have Wide Possibilities, reprint from TheNCR Factory News, October 1959, The National Cash Register Company,Dayton. 9, Ohio.

Varden: Modern Photography, 1959, page 86.

NORMAN G. TORCHIN, Primary Examiner. HAROLD N. BURSTEIN, Examiner.

1. A PHOTOGRAPHIC ELEMENT COMPRISING A SILVER HALIDE EMULSION AND INTEGRAL THEREWITH A WATER-PERMEABLE, HYDROPHILIC COLLOID LAYER ON A SUPPORT, SAID LAYER COMPRISING (1) A CONTINUOUS PHASE OF WATER-PERMEABLE, HYDROPHILIC COLLOID, AND UNIFORMLY DISPERSED THROUGHOUT SAID CONTINUOUS PHASE, (2) A DISCONTINUOUS PHASE OF HEAT SENSITIVE CAPSULES EACH COMPRISING A CORE CONTAINING (A) A SOLUTION IN AN OILY, WATER-IMMISCIBLE SOLVENT OF A SILVER HALIDE PROCESSING REAGENT SELECTED FROM THE GROUP CONSISTING OF SILVER HALIDE PHOTOGRAPHIC DEVELOPERS, FIXERS AND COMBINED DEVELOPERS AND FIXERS, (B) A HEAT-DECOMPOSABLE, GAS-PRODUCING, ORGANIC COMPOUND COMPATIBLE WITH SILVER HALIDE PHOTOGRAPHIC EMULSION, HAVING AT LEAST 2 NITROGEN ATOMS LINKED TOGETHER, SAID NITROGEN ATOMS BEING LIBERATED BY HEAT AT A TEMPERATURE OF ABOUT 60*C. TO ABOUT 150*C. TO PRODUCE NITROGEN GAS, AND (C) SURROUNDING SAID CORE, A SHELL OF A GELATIN-GUM ARABIC COACERVATE. 